Preparation and characterization the portland cement clinker produced at the semi industrial rotation kiln : diploma thesis

Proizvodnja portland cementa predstavlja složen tehnološki proces u kojem se sirovina, vapnenac i glina, bitno mijenjaju i transformiraju termičkom obradom stvarajući cementni klinker koji nakon mljevenja s gipsom predstavlja konačni proizvod - portland cement. Klinker kao osnovni sastojak portland cementa dobiva se pečenjem sirovine koja sadrži okside kalcija, silicija, aluminija i željeza. Sinteriranjem pri temperaturi od oko 1450 °C nastaju minerali klinkera o kojima ovise konačna svojstva cementa poput čvrstoće, topline hidratacije, kemijske otpornosti, trajnosti i dr. U portland cementnom klinkeru formiraju se četiri glavna minerala klinkera i to: trikalcijev silikat ( 3 ), dikalcijev silikat ( 2 ), trikalcijev aluminat ( 3 ) i tetrakalcijev aluminat - ferit ( 4 ). Proizvodnja portland cementa, počevši od kamenoloma do gotovog proizvoda, mora biti pod stalnim nadzorom i kontrolom. U eksperimentalnom dijelu rada pripravljena je sirovina na poluindustrijskom mlinu te je ista analizirana primjenom laserske difrakcije u cilju utvrđivanja distribucije i veličine čestica u pripravljenoj smjesi. Udjel korektivnih komponenti je određen elementarnom analizom primjenom XRF metode. Konačno dobiveni portland cementni klinker analiziran je primjenom metode difrakcije X-zraka (XRD), termogravimetrije/diferencijalne termogravimetrije i diferencijalne toplinske analize (TG/DTG-DTA) te optičkom mikroskopijom u tamnom polju. Rezultati mjerenja dobiveni korištenjem različitih instrumentih metoda na proizvedenom klinkeru ukazuju da su uvjeti u peći dostatni za sintezu minerala klinkera, međutim oscilacije koje su vidljive u usporedbi dobivenih rezultata na različim uzorcima klinkera ukazuju na oscijalacije u kvaliteti proizvedenog klinkera.The production of the portland cement represents complicated technological process in which raw material, limestone and clay are fundementally changed and transformed by thermic treatment, producing cement clinker that after mixing with gypsum represents the final product – the portland cement. Clinker as the essential component of the Portland cement, is made by burning raw meal that containes oxides of calcium, silicon, aluminum and iron. By sintering at about 1450 o C, clinker minerals form that the final performance of cement depends, like hardness, thermal hydration, chemical resistance, durability and so on. In Portland cement clinker, four principal minerals are formed and that: tricalcium silicate (C 3 S), dicalcium silicate (C 2 S), tricalcium aluminate (C 3 A) and tetracalcium alumo- ferrite (C 4 AF). The production of Portland cement, starting at the quarry to the final product, must be under constant supervise and control. In the experimental part of the work, the raw material is prepared on semi industrial mill, and is analysed by laser diffraction apply to determine distribution and size of particles in the prepared mixture. The contribution of corrective components is determined by elemental analysis with the XRF method application. The final product – the portland cement clinker, is analized by use of the X-Ray Diffraction method (XRD), Thermogravimetry/Differential Thermogravimetry – Differential Thermal Analaysis (TG/DTG-DTA), and by optical microscopy in the darkfield. The results of the measurments aquired by different instrumental methods on the produced clinker show that conditions in the furnace are adequate for the synthesis of clinker minerals. However, oscilations of the results on the different clinker samples, indicate the oscilations of the quality of clinker product

Primjena eteričnih ulja za masažu

Many plant species have been used for the massage mainly in the form of essential oils. The most common oils are obtained from the following plant species: Lavandula angustifolia, Rosmarinus officinalis, Mentha x piperita, Melaleuca alternifolia, Eucalyptus globulus, Citrus limon, Citrus aurantium ssp. dulcis, Citrus reticulata, Cinnamomum zeylanicum, Syzygium aromaticum, Pinus silvestris and Pelargonium x asperum. Applications of essential oils for therapeutic purporses are numerous (i.e., wellbeing, labour, infections, dementia and anxiety treatment) but often they have not been scientifically validated

Evaluation of the Locking Compression Plates Stress-Strain Fields

Locking Compression Plates (LCP) have found application in the orthopaedic healing process in modern medicine. Their design is specifically modified depending on the bone and the loading the specific bone is subjected to. Dimensions of LCP, as well as mechanical characteristics, provide greater structural resistance than the bone itself; in practice, however, continuous application and cyclic loading can lead to fails and fractures. Defining of the testing approaches and procedures used for the evaluation of the stress and location of geometrical areas with potential risk of the stress concentration represent the aim of this investigation. Results obtained in this paper show that combined use of modern experimental methods (DIC) and numerical simulations on the modified and simplified LCP geometry, can be used to locate stress and strain fields, as well as areas with stress concentration that can result in the appearance of cracks during cyclic loading

Thromboprophylaxis in pregnant patient-specific risks

Background: Pregnancy and the puerperium are well-established risk factors for venous thromboembolism. Prothrombotic changes start after conception and normal coagulation returns eight weeks after the labour. The risk of DVT is approximately twice as high after caesarean delivery than vaginal birth. Specific risks: Inherited or acquired thrombophilias increase thromboembolic risk and influence the approach to thromboprophylaxis. Additional factors that increase thrombotic risk include immobilisation, such as bed rest for pregnancy complications, surgery including caesarean section, ovarian hyperstimulation during gonadotropin use for in vitro fertilisation, trauma and malignancy. The preferred agents for thromboprophylaxis in pregnancy are heparin compounds; these agents do not cross the placenta and therefore appears safe for the fetus. Because of the theoretical risk of epidural spinal haemorrhage in women receiving heparin that undergo epidural or spinal anaesthesia many anaesthesiologist will not perform neuraxial regional anaesthesia in women who have recently received heparin. Anaesthesia guidelines advise waiting to insert the needle at least 10 to 12 hours after the last prophylactic dose of LMWH, and at least 24 hours after the last therapeutic dose. Conclusion: Despite the increased risk of thrombosis in pregnancy, anticoagulants are not routinely indicated, because the risks usually outweigh the benefits. The exception is women on life-long anticoagulation or women with history of thrombosis or thrombophylia.Heparin therapy must be interrupted temporarily during the immediate peripartum interval to minimise the risk of haemorrhage and to allow for the option of regional anaesthesia

3D Cell Technology in Biomedical Research

Traditional two dimensional cell culture has enabled great strides in biomedicine but needs to be improved to be able to keep up with the demands of modern biomedical research. 2D monolayer culture cannot replicate tissue responses and needs to be supplemented with extensive animal research. Growing cells in three dimensional scaffolds provides a more functional model for biomedical research than traditional monolayer culture. Depending on the needs and the complexity of the model there are several ways that 3D models can be initiated. Simple spheroids can be grown in low adherence plates and in hanging drops while larger spheroids and co-cultured ones need to be grown in systems with greater support such as hydro gels. The system that offers the greatest flexibility is the magnetic levitation approach. In the paper we offer a brief resume to various 3D methods and their characteristics to ease the choice of methods for implementing 3D cell culture techniques

Ternary Coordination Compounds of Copper(II) with Glycine and 2,2\u27-bipyridine: Synthesis, Structural Characterization, Magnetic and Biological Properties

Three new coordination compounds of copper(II) with glycine (HGly) and 2,2\u27-bipyridine (bipy) were synthesized by solution-based and mechanochemical methods: [Cu(Gly)(H2O)(bipy)][Cu(Gly)(SO4)(bipy)]·6H2O (1a·6H2O), [Cu(Gly)(H2O)(bipy)]2SO4 (1b), [Cu(Gly)(H2O) (bipy)]2SO4·H2O (1b·H2O). The amount of water in the reaction mixture influenced the product of crystallization. All compounds were characterized by X-ray diffraction methods and form 1D infinite chains or 2D sheets of complex ions connected by π-interactions. Compounds 1a·6H2O and 1b were characterized by X-band electron spin resonance (ESR) spectroscopy and the values of g-tensors for Cu(II) ions were determined. Compounds 1a·6H2O and 1b showed pronounced antiproliferative activity toward a panel of six human cell lines. The most impared was HepG2 cell line at 10−5 mol dm−3 concentration (74.5 % reduction of cell growth) followed by moderate activity toward KATO III, Caco-2, MDA-MB-231, PANC-1 and MRC-5 cells at 10−4 mol dm−3 concentration of compounds 1a·6H2O and 1b. Generally, both compounds express similar antiproliferative effect on evaluated cells

Comparative Exemination of the Strengthened and Non-Strengthened NIMONIC Specimens with Laser Shot Peening Method

Laser shot peening (LSP) of material strengthening is nowdays widely used method in various branches of industry. In this paper are presented comparative exeminations of specimen made of NIMONIC and strengthened specimen on which laser shot peening method was performed. Specimens were made as thin plates with holes. Macrostructural surface tests were performed around the specimens holes with different magnifications for both specimens as well as certain damages on the specimens. 3D images of specimens damages provide insights into the its dimensions. In addition, the roughness of non-strengthed and strengthed specimens was also performed. Hardness tests using the Rockwell C method of both specimens show a difference in the hardness of both samples and the main characteristics of the laser shot peening method. Also, the analysis on how the damage of samples could represent the location of initial cracks that could cause failure of the specimens or generally machine part is given as well

Laser Processing of Ni-Based Superalloy Surfaces Susceptible to Stress Concentration

Reliable and resilient constructions are basic for ensuring the safety of various structures. The superalloys are used as constructive materials due to their superb mechanical properties and endurance. However, even these materials can have certain areas where the stress concentration is higher than expected, such as drilling holes, which are common in various structures that need additional enhancement. Surface laser modifications of the areas surrounding the holes drilled in Nimonic 263 sheets are done by pulsed picosecond and nanosecond Nd:YAG laser irradiations with pulse durations of 170 ps and lt = 8 ns, respectively. Following the laser surface treatment, the effectiveness of the enhancement was analyzed by the microhardness test and the deformation test. The results show that the deformation and stress values are decreased by 25-40 percent, showing the improvement in the resilience to deformation. The Vickers microhardness test results indicate an improvement in the Nimonic 263 microhardness. The dimensions of the microcracks are higher for the untreated material in comparison to the laser-treated material

Laser Processing of Ni-Based Superalloy Surfaces Susceptible to Stress Concentration

Reliable and resilient constructions are basic for ensuring the safety of various structures. The superalloys are used as constructive materials due to their superb mechanical properties and endurance. However, even these materials can have certain areas where the stress concentration is higher than expected, such as drilling holes, which are common in various structures that need additional enhancement. Surface laser modifications of the areas surrounding the holes drilled in Nimonic 263 sheets are done by pulsed picosecond and nanosecond Nd:YAG laser irradiations with pulse durations of 170 ps and lt = 8 ns, respectively. Following the laser surface treatment, the effectiveness of the enhancement was analyzed by the microhardness test and the deformation test. The results show that the deformation and stress values are decreased by 25-40 percent, showing the improvement in the resilience to deformation. The Vickers microhardness test results indicate an improvement in the Nimonic 263 microhardness. The dimensions of the microcracks are higher for the untreated material in comparison to the laser-treated material

Antineoplastic DNA-binding compounds: intercalating and minor groove binding drugs

DNA intercalating and minor groove binding compounds are new weapons in the battle against malignant diseases. These antineoplastic agents target the DNA molecule and interfere with the cell cycle leading to rapidly proliferating cell death. They are mainly derivates of a naturally occurring organic compound derived from a microorganism or plant. Intercalators usually act as topoisomerase I and/or II poisons, while the mechanisms of DNA minor groove binders are a combination of several steps including topoisomerase poisoning. This paper gives an overview of some of the developed DNA intercalating and minor groove binding compounds, as well as an explanation of their chemical structures, origins, and application in chemotherapy